Beginning about AD 800, the Danes began a long era of well organised raids across the coasts and rivers of Europe. Some of the raids were followed by a gradual succession of Danish settlers. In the British Isles, the Danes began settling England in 865, when brothers Halfdan Ragnarsson and Ivar the Boneless wintered in East Anglia. Halfdan and Ivar moved north and captured Northumbria in 867 and York as well. Danelaw - a special rule of law - was soon established in the settled areas and shaped the local cultures there for centuries. Cultural remains are still noticeable today.[3] The Danes invaded Ireland in 853 and were followed by Danish settlers who gradually assimilated with the local population and adopted Christianity.

^Anderson, Carl Edlund. "The Danish Tongue and Scandinavian Identity"(PDF). p. 1. Retrieved 4 November 2013. Icelandic writers (who provide the bulk of our surviving documentation)commonly employed the term dǫnsk tunga (literally “Danish tongue”) to identify the language not just of those who were ruled by the Dana konungr, but of all Germanic-speaking Scandinavians.